1. Field of the Invention
The invention relates to a control device and method, and more particularly to a control device and method for a motor.
2. Description of the Related Art
For conventional control methods for brushless motors, a pulse width modulation (PWM) signal is used to control a driving circuit which further provides current to a stator of a motor, so that polarities are generated in the stator. The motor rotates by the influence of a rotor with a permanent magnet and the stator with the polarities. When the motor rotates to a predetermined angle, the polarities of the stator are changed, and the motor continuously rotates. By providing the PWM signal to the driving circuit and continuously changing the polarities of the stator, the motor can unceasingly rotate. However, because a PWM is continuously provided to the driving circuit, power consumption of the driving circuit is increased. Additionally, when the polarities of the stator are changed, surge current is generated due to the switch operation of the driving circuit, degrading efficiency of the driving circuit.
It is desired to provide a control device and method for a motor, which can improve efficiency and save power of a driving circuit by controlling the switching of a PWM signal.